Definition of foramen magnum in US English:

foramen magnum


  • The hole in the base of the skull through which the spinal cord passes.

    • ‘The cysts may localize anywhere within the CNS, but are often found at the base of the brain around the foramen magnum or surrounding the spinal cord.’
    • ‘At the level of the foramen magnum, where the spinal cord ends and the medulla oblongata begins, the gray matter undergoes a marked reorganization.’
    • ‘The root lies dorsal to the rootlets of the 1st cervical nerve and the vertebral artery and can be followed through the foramen magnum into the cranial cavity.’
    • ‘A malformed brain stem was attached to the foramen magnum.’
    • ‘Located at the base of the skull, the medulla oblongata is continuous with the spinal cord at the foramen magnum.’


Latin, ‘large opening’.